Fetal Alcohol Spectrum Disorder (FASD) is a leading cause of life-long deficits in behavior and cognitive function and psychiatric co-morbidities that affect 1/100 live births. Due to a lack of distinct facial features and effective diagnostic tools, many cases are missed or diagnosed late, which causes enormous family, school, and socioeconomic distress. High computational brain imaging is being investigated as a new diagnostic tool, but it is costly and progress has been limited. Here, we propose a novel approach of using the placenta as a surrogate tissue for detecting epigenetic biomarkers that are altered by prenatal alcohol exposure in the brain. Epigenetic modifications are intrinsically programmed during fetal development, but this developmental program can be altered by environmental factors. Alcohol, like folic acid, is a proven epigenetic modifier in fetal tissues, which acts by metabolically altering the availability of methyl donors. Neurodevelopmental deficit is a prerequisite of FASD, and we have found that fetal alcohol exposure highly affected the epigenetic program, including 5-methylcytosine (5mC) and 5-hydroxylmethylcytosine (5hmC), in the compromised developing neural tube and brain. In addition, we have recently found that placenta is a highly comparable alcohol-responsive tissue. In this proposal, we will characterize epigenetic marks such as DNA methylation, including 5mC and 5hmC, and/or histone modifications at the cellular and epigenomic levels in the placenta using a mouse model of FASD in parallel with placentas from children with an FASD. Our working hypothesis is that alcohol alters a common developmental epigenetic program in fetal tissues including the embryonic brain and the placenta, and that these epimutations are conserved in mice and humans. We plan to test this hypothesis by comparing alcohol altered epigenetic marks in the embryonic brain and its paired placenta. Since such work cannot be ethically performed in humans, we propose a translational study to validate the alcohol-epigenetic signature found in the embryonic brain and placenta of an FASD mouse model with human placentas from FASD children. We will first conduct a comparative epigenetic analysis in both mouse and human FASD placental tissues at the cellular level (Specific Aim 1), and then investigate DNA methylation epimutations in the fetal FASD mouse brain and its paired placenta at the genomic level (methylome) (Specific Aim 2). Next generation sequencing of methylated cytosines will be adopted to identify epimutations throughout the genome. The statistically high candidate sets of genes or intergenic regions that are commonly altered by alcohol in both mouse embryonic brain and its paired placenta will be identified and further validated in human placentas from FASD children at a single nucleotide resolution by pyrosequencing. The funding of this proposal will foster a collaborative translational research study that will lay an important new basis for early diagnosis of an FASD in children.